Dual clutch transmission with radially nested clutches having a common disk carrier

ABSTRACT

A dual clutch transmission having radially nested clutches including an outer clutch having first inner and outer clutch disks that are interleaved between each other where the first outer clutch disks are operatively mounted to a first outer support carrier. The transmission also includes an inner clutch having second inner and outer clutch disks operatively interleaved between each other and operatively mounted to a second inner support carrier. A common disk carrier has a common clutch disk carrier that operatively supports the first inner clutch disks of the outer clutch and the second outer clutch disks of the inner clutch.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. Ser. No. 11/146,844, entitled“Dual Clutch Transmission with Radially Nested Clutches Having a CommonDisk Carrier” filed Jun. 7, 2005.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates, generally to a dual clutch transmissionand, more specifically, to a dual clutch transmission with radiallynested clutches having a common disk carrier.

2. Description of the Related Art

Power shifting transmissions used in motor vehicles are employed totransfer power from the prime mover, or engine, to the driven wheels.Power shifting transmissions can take the form of a dual, or twin,clutch transmission where the torque input from the engine is deliveredto two input shafts each supporting a portion of the gear sets. Eachinput shaft has an associated clutch to selectively transfer torqueprovided by the engine. Since the input engine torque comes through asingle input member, such as the flywheel or crankshaft, one structuralarrangement for the dual clutch assembly is to dispose the two clutchassemblies in a single radially nested arrangement. The dual clutchassembly is operatively disposed about the two input shafts, which arealso in a co-axial and co-centric arrangement. To selectively engage anddisengage their respective input shafts, the two clutches of the dualclutch transmission are each comprised of a set of clutch discs, alsoreferred to as a clutch pack. The clutch packs each include one set ofdiscs physically coupled to one of the input shafts and another set ofdiscs physically coupled to the torque input member. The two sets ofclutch discs in each clutch pack are alternately supported by inner andouter disc supports. The clutches are engaged by compressing the twosets of discs together against a fixed back plate.

The conventional structure of radially nested dual clutches comprises anouter clutch with an outer disk carrier supporting the outer disks ofthe outer clutch and an inner disk carrier supporting the inner disks ofthe outer clutch. An inner clutch is radially nested within the outerclutch and includes an outer disk carrier supporting the outer disks ofthe inner clutch and an inner disk carrier supporting the inner disks ofthe inner clutch. Each clutch comprises an actuating piston to cause theinner and outer disks of the respective clutch to frictionally engageeach other and thereby transfer torque from the torque input member tothe respective input shaft.

Each piston is axially movable and is guided by a corresponding radialcylinder. The cylinder and actuating piston form a pressure chamber,which can be pressurized by hydraulic fluid in order to bring the disksinto (or if necessary out of) frictional engagement. Frequently, acompensating piston is additionally assigned to one or both actuatingpistons. The actuating piston and the compensating piston form acompensating chamber. The compensating chamber can also be supplied withhydraulic fluid to compensate for an excess of pressure in the pressurechamber caused by centrifugal force, which occurs in the case ofincreasing speed. In most conventional designs, although radiallynested, the two clutches are entirely separate and individuallycomplete. In some variants, the compensating chamber of the outer clutchis formed by the actuating piston of the outer clutch and the outer diskcarrier of the inner clutch.

Although the structure of the conventional dual clutches assembliesmentioned above is generally adequate for the intended purpose, theyprovide radially nested dual clutch assemblies that are needlesslycomplex and bulky. In the conventional designs, the clutch assembliesare separate each having inner and outer disk support carriers, innerand outer radial guide cylinders, inner and outer compensating pistons,and inner and outer actuating pistons. Thus, the size and weight of theconventional radially nested dual clutch assemblies cause parasiticlosses that reduce the efficiency of the transmission and the vehicle.Further, the combination of the numerous nested components is difficultto assemble adding to its overall production costs.

Accordingly, there remains a need in the related art for a dual clutchtransmission having a radially nested dual clutch assembly with fewercomponents, which allows for a lighter, more compact, and more efficientdual clutch assembly. There also remains a need for this type oftransmission having a radially nested dual clutch assembly that providesgreater efficiency, more cost effective production, and ease of assemblyby employing fewer components.

SUMMARY OF THE INVENTION

The disadvantages of the related art are overcome by the presentinvention which is directed toward a dual clutch transmission havingradially nested clutches. The dual clutch transmission includes an outerclutch having a plurality of first outer clutch disks, a plurality offirst inner clutch disks and a first outer support carrier. The firstinner clutch disks and the first outer clutch disks are operativelyinterleaved between each other and the first outer clutch disks areoperatively mounted to the first outer carrier. The transmission furtherincludes an inner clutch having a plurality of second outer clutchdisks, a plurality of second inner clutch disks, and a second innersupport carrier. The second inner clutch disks and the second outerclutch disks are operatively interleaved between each other and thesecond inner clutch disks are operatively mounted to the second innercarrier. In addition, the dual clutch transmission of the presentinvention includes a common disk carrier having a common clutch diskcarrier that operatively supports the first inner clutch disk of theouter clutch and a second outer clutch disk of the inner clutch.

In this manner, the radially nested dual clutch assembly for a dualclutch transmission of the present invention has the advantages ofreducing weight and space requirements due to reducing the number ofnecessary components, which increases transmission and vehicleefficiency. Furthermore, the present invention overlaps the actuatingand compensating chambers that are employed to control the operation ofthe clutches. Thus, the manufacturing process is also simplified andmade more efficient.

Other objects, features and advantages of the present invention will bereadily appreciated, as the same becomes better understood after readingthe subsequent description taken in connection with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-section view of the radially nested clutches having acommon disk carrier for a dual clutch transmission of the presentinvention;

FIG. 2 is a cross-section view illustrating another example of themanner of assembly for the common disk carrier of the present inventionshown in FIG. 1;

FIG. 3 is a cross-section view illustrating still another example of themanner of assembly for the common disk carrier of the present inventionshown in FIG. 1; and

FIG. 4 is a cross-section view of another embodiment of the radiallynested clutches having a common disk carrier for a dual clutchtransmission of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

The radially nested dual clutch assembly of a dual clutch transmissionin accordance with the present invention is illustrated in FIG. 1. Thedual clutch assembly comprises an outer clutch 1 and an inner clutch 2.The outer clutch 1 has a plurality of first outer clutch disks 20, aplurality of first inner clutch disks 22, and a first inner supportcarrier 17. The first inner clutch disks 22 and the first outer clutchdisks 20 are operatively and alternately disposed between each other,with the first inner clutch disks 22 operatively mounted to the firstinner carrier 17. The inner clutch 2 has a plurality of second outerclutch disks 21, a plurality of second inner clutch disks 23, and asecond inner support carrier 16. The second inner clutch disks 23 andthe second outer clutch disks 21 are operatively and alternatelydisposed between each other, with the second inner clutch disks 23operatively mounted to the second inner carrier 16. The radially nesteddual clutch assembly also includes a common disk carrier 7 having afirst outer clutch disk carrier 7 a that operatively supports the firstouter clutch disks 20 of the outer clutch 1 and a second outer clutchdisk carrier 12 that operatively supports the second outer clutch disks21 of the inner clutch 2.

More specifically, the ring-shaped outer disks 20 and 21 and inner disks22 and 23 engage one another alternately within their respective outerand inner clutches 1 and 2 to each form a clutch pack. As shown in FIG.1, the disks 20, 22 of the outer clutch 1 and the disks 21, 23 of theinner clutch 2 are co-axially arranged about an axis of rotation “ax”,with the clutch pack of the inner clutch 2 radially arranged, or nestedwithin the clutch pack of the outer clutch 1. In the preferredembodiment, the plurality of outer disks 20 are operatively retainedwithin the first outer disk carrier 7 by raised portions 7 b thatcorrespond to notches or grooves in the outer disks 20. The plurality ofouter disks 21 likewise retained within the second outer disk carrier 12by raised portions 12 a that correspond to notches or grooves in theouter disks 21. Both sets of inner disks 22 and 23 are first mounted tosleeves that are inserted in the respective inner disk carriers 17 and16. It should be appreciated that the sleeves that retain the disks ofthe clutch packs may be mounted within the inner and outer carriers byany of a variety of attachment methods, such as a splined connection, orwelding, for example. It should be further appreciated that within thescope of the present invention the sleeves may be omitted such that theinner and outer disks are directly mounted to, and retained on thecarriers.

A first actuating piston 9 is adapted to cause the first inner and firstouter disks 20, 22 of the outer clutch 1 to operatively engage eachother, and a second actuating piston 3 is adapted to cause the secondinner and said second outer disks 21, 23 of the inner clutch 2 tooperatively engage each other. The actuating pistons 3 and 9 can beselectively actuated to move axially to the right (as illustrated inFIG. 1) to cause the inner and outer disks of the clutch packs to bebrought into frictional engagement with each other. The dual clutchassembly further includes a guide cylinder 11 wherein actuating piston 9is disposed between the guide cylinder 11 and the common disk carrier 7such that the guide cylinder 11 and actuation piston 9 form a pressurechamber 10 that is adapted to be pressurized to cause actuating piston 9to actuate the outer clutch 1. Actuation piston 9 and the common diskcarrier 7 also form a compensation chamber 8 that is adapted to bepressurized to compensate for excess outer clutch actuation pressure.Thus, actuating piston 9 is guided in its axial displacement along thecorresponding guide cylinder 11.

The dual clutch assembly further includes a compensating piston 4wherein the actuating piston 3 is disposed between the compensatingpiston 4 and the common disk carrier 7 such that the common disk carrier7 and actuation piston 3 form a pressure chamber 6 that is adapted to bepressurized to cause actuating piston 3 to actuate the inner clutch 2.Actuation piston 3 and the compensating piston 4 form a compensationchamber 5 that is adapted to be pressurized to compensate for excessinner clutch actuation pressure. Thus, the actuating piston 3 is guidedalong an axial portion of the common disk carrier 7. The two pressurechambers 6, 10 can be pressurized independently from each other byselectively supplying pressurized hydraulic fluid.

The actuating pistons 3 and 9 are returned to their disengaged positionby the biasing force of spring disks 18 and 19, respectively. Wheneither of the pressure chambers 6, 10 are selectively pressurized, therespective actuating pistons 3, 9 are moved against the biasing force ofthe spring disks 18, 19 to engage the disks of the clutch pack.Additionally, clutch assembly 2 includes a compensating piston 4 thatcooperates with the corresponding actuating piston 3 to form acompensating chamber 5. Similarly, clutch assembly 1 employs an axialportion of the common disk carrier 7 that cooperates with actuatingpiston 9 to form a compensating chamber 8. During the operation of thetransmission, as the clutch assemblies 1 and 2 rotate, the compensatingchambers 5 and 8 are supplied with hydraulic fluid that is pressurizedby the outward centrifugal movement of the hydraulic fluid. Thecentrifugal hydraulic fluid in the compensating chambers 5, 8compensates for an excess of pressure in the respective pressurechambers 6, 10 that also arises due to the outward centrifugal forcegenerated by the rotation of the clutch assemblies 1 and 2.

The radially nested dual clutch of the present invention selectivelytransfers torque from the prime mover to the two input shafts of thetransmission. As shown in FIG. 1, a motor drive shaft 24 provides theinput torque to a torque input disk 25, to the common disk carrier 7,and to first outer disk carrier 7 a of the outer clutch 1 and to thesecond outer disk carrier 12 of inner clutch 2. Thus, the respectiveouter clutch disks 20 and 21 of the outer clutch 1 and the inner clutch2 operatively rotate with the torque input disk 25. As previouslymentioned, the dual clutch transmission includes two input shafts asillustrated at 30 and 31 in FIG. 1. The inner disk carrier 16 of theinner clutch 2 is operatively mounted to the first input shaft 31 by asplined connection at 29 and the inner disk carrier 17 of the outerclutch 2 is operatively mounted to the second input shaft 30 by asplined connection at 28.

The outer disk carrier 12 of the inner clutch 2 is formed to include aplurality of teeth 26 running in axial direction ax that engagecorresponding openings 27 in the common disk carrier 7. The engagementof the teeth 26 within the openings 27 axially locks the two outer diskcarriers 7 a and 12 to each other, making them essentially a singularelement. The outer disk carrier 7 a of the outer clutch 1 is furtherfixed to the clutch hub 13 that is axially supported by the input shafts30 and 31. In this manner, torque provided by the motor drive shaft 24can now be transferred to the input shaft 30 by pressurizing thepressure chamber 10 to cause the actuating piston 9 to move againstclutch pack of the outer clutch 1 so that torque is transferred throughthe clutch pack to the inner disk carrier 17. Torque may also betransferred to the input shaft 31 by pressurizing the pressure chamber 6to cause the actuating piston 3 to move against the clutch pack of theinner clutch 2 so that torque is transferred through the clutch pack tothe inner disk carrier 16.

In order to achieve the greatest possible space savings and componentreduction, the dual clutch of the present invention is designed in sucha way that the actuating piston 9 of the outer clutch 1 penetrates thecommon disk carrier 7 of the outer clutch 1. The actuating piston 9 ofthe outer clutch 1 includes a plurality of extending tabs, or fingers 9aarranged circumferentially that extend through corresponding openings 14in the common disk carrier 7. When the actuating piston 9 is actuated,the extending tabs 9a operatively engage the clutch pack of the outerclutch 1. Further, the pressure chambers 6, 10 and compensating chambers5, 8 are radial arranged to overlap and fit within each other to saveradial and axial space.

In addition to the construction of the common disk carrier 7 thatincludes first and second outer disk carriers 7A and 12 as discussedabove and illustrated in FIG. 1. FIG. 2 illustrates another method ofproducing the common disk carrier 7, where like numerals are used todesignate like structure. More specifically, instead of the first singleouter disk carrier 7 having the second outer disk carrier 12 mounted byteeth 26 and openings 27, the common disk carrier 7 in FIG. 2 employs acarrier plate 15. The carrier plate 15 includes separate outer diskcarriers 7 a and 12 that are operatively mounted to the carrier plate 15at 15 a and 15 b, respectively. It should be appreciated that attachmentof the carriers to the plate may be any of a variety of methods such aswelding, or teeth with corresponding openings, for example.

Furthermore, another embodiment of the common disk carrier 7 is shown inFIG. 3. In this case, an outer disk carrier 12 c is formed as a singlepiece for the inner clutch 2 and a separate outer disk carrier 7 c forthe outer clutch 1 is mounted to the outer disk carrier 12c at 33. Inthe preferred embodiment of the present invention as shown in FIG. 3,the outer disc carrier 7 c is welded to the outer disk carrier 12 c.

FIG. 4 shows another embodiment of the present invention of a dualclutch transmission with radially nested clutches having a common diskcarrier. In this case, the dual clutch assembly includes an outer clutch41 and an inner clutch 42. The outer clutch 41 has a plurality of firstouter clutch disks 20, a plurality of first inner clutch disks 22, andan outer support carrier 57. The first inner clutch disks 22 and thefirst outer clutch disks 20 are operatively and alternately disposedbetween each other, with the first outer clutch disks 20 operativelymounted to the outer carrier 57. The inner clutch 42 has a plurality ofsecond outer clutch disks 21, a plurality of second inner clutch disks23, and a second inner support carrier 52. The second inner clutch disks23 and the second outer clutch disks 21 are operatively and alternatelydisposed between each other, with the second inner clutch disks 23operatively mounted to the second inner carrier 52. The radially nesteddual clutch assembly also includes a common disk carrier 47 having acommon disk carrier 47 a that operatively supports the first innerclutch disks 22 of the outer clutch 1 and the second outer clutch disks21 of the inner clutch 42.

More specifically, the ring-shaped outer disks 20 and 21 and inner disks22 and 23 engage one another alternately within their respective outerand inner clutches 41 and 42 to each form a clutch pack. As shown inFIG. 4, the disks 20, 22 of the outer clutch 41 and the disks 21, 23 ofthe inner clutch 42 are co-axially arranged around an axis of rotation“ax”, with the clutch pack of the inner clutch 42 radially arranged, ornested within the clutch pack of the outer clutch 41 about the commondisk carrier hub 47a. Each clutch assembly 41, 42 includes an actuatingpiston 43 and 49, respectively. The pistons 43 and 49 can be actuated tomove axially to the right (as illustrated in FIG. 4) to cause the innerand outer disks of the clutch packs to be brought into frictionalengagement with each other. The dual clutch assembly further includes aguide cylinder 51 wherein actuating piston 49 is disposed between theguide cylinder 51 and the common disk carrier 47 such that the guidecylinder 51 and actuation piston 49 form a pressure chamber 50 that isadapted to be pressurized to cause actuating piston 49 to actuate theouter clutch 41. Actuation piston 49 and the common disk carrier 47 alsoform a compensation chamber 48 that is adapted to be pressurized tocompensate for excess outer clutch actuation pressure. Thus, actuatingpiston 49 is guided in its axial displacement along the correspondingguide cylinder 51.

The dual clutch assembly further includes a compensating piston 44wherein the actuating piston 43 is disposed between the compensatingpiston 44 and the common disk carrier 47 such that the common diskcarrier 47 and actuation piston 43 form a pressure chamber 46 that isadapted to be pressurized to cause actuating piston 43 to actuate theinner clutch 42. Actuation piston 43 and the compensating piston 44 forma compensation chamber 45 that is adapted to be pressurized tocompensate for excess inner clutch actuation pressure. Thus, theactuating piston 43 is guided along an axial portion of the common diskcarrier 47. The two pressure chambers 46, 50 can be pressurizedindependently from each other by selectively supplying pressurizedhydraulic fluid.

The actuating pistons 43 and 49 are returned to their disengagedposition by the biasing force of spring disks 58 and 59, respectively.When either of the pressure chambers 46, 50 are selectively pressurized,the respective actuating pistons 43, 49 are moved against the biasingforce of the spring disks 58, 59 to engage the disks of the clutch pack.The actuating pistons 43 and 49 are returned to their disengagedposition by the biasing force of spring disks 58 and 59, respectively.When either of the pressure chambers 46, 50 are selectively pressurized,the respective actuating pistons 43, 49 are moved against the biasingforce of the spring disks 58, 59 to engage the disks of the clutch pack.Additionally, clutch assembly 42 includes a compensating piston 44 thatcooperates with the corresponding actuating piston 43 to form acompensating chamber 45. Similarly, clutch assembly 41 employs an axialportion of the common disk carrier 47 that cooperates with actuatingpiston 49 to form a compensating chamber 48. During the operation of thetransmission, as the clutch assemblies 1 and 2 rotate, the compensatingchambers 45 and 48 are supplied with hydraulic fluid that is pressurizedby the outward centrifugal movement of the hydraulic fluid. Thecentrifugal hydraulic fluid in the compensating chambers 45, 48compensates for an excess of pressure in the respective pressurechambers 46, 50 that also arises due to the outward centrifugal forcegenerated by the rotation of the clutch assemblies 41 and 42.

The radially nested dual clutch of the present invention as shown inFIG. 4 provides to selectively transfer torque from the prime mover tothe two input shafts of the transmission. In this case, a motor driveshaft 24 provides the input torque to a torque input disk 25 and to thecommon disk carrier 47 of the outer clutch 41 and inner clutch 42. Thus,the respective inner clutch disks 21 of the outer clutch 41 and theouter clutch disks 21 of the inner clutch 42 operatively rotate with thetorque input disk 25. As previously mentioned, the dual clutchtransmission includes two input shafts as illustrated at 30 and 31 inFIG. 4. The inner disk carrier 52 of the inner clutch 42 is operativelymounted to the first input shaft 31 by a splined connection at 29 andthe outer disk carrier 57 of the outer clutch 42 is operatively mountedto the second input shaft 30 by a splined connection at 28.

The common disk carrier 47 is further fixed to the clutch hub 13 that isaxially supported by the input shafts 30 and 31. In this manner, torqueprovided by the motor drive shaft 24 can now be transferred to the inputshaft 30 by pressurizing the pressure chamber 50 to cause the actuatingpiston 49 to move against the clutch pack of the outer clutch 41 so thattorque is transferred through the clutch pack to the outer disk carrier57. Torque may also be transferred to the input shaft 31 by pressurizingthe pressure chamber 46 to cause the actuating piston 43 to move againstclutch pack of the inner clutch 42 so that torque is transferred throughthe clutch pack to the inner disk carrier 52.

In order to achieve the greatest possible space savings and componentreduction, the dual clutch of the present invention is designed in sucha way that the actuating piston 49 of the outer clutch 41 penetrates thecommon disk carrier 47. The actuating piston 49 of the outer clutch 41includes a plurality of extending tabs, or fingers 49a arrangedcircumferentially that extend through corresponding openings 54 in thecommon disk carrier 47. When the actuating piston 49 is actuated, theextending tabs 49 a operatively engage the clutch pack of the outerclutch 41. Further, the pressure chambers 46, 50 and compensatingchambers 45, 48 are radially arranged to overlap and fit within eachother to save radial and axial space.

Thus, the radially nested dual clutch assembly for a dual clutchtransmission of the present invention employs a common disk carrier thathas the advantage reducing weight and space requirements due to reducingthe number of necessary components, which increases transmission andvehicle efficiency. Furthermore, the present invention overlaps theactuating and compensating chambers that are employed to control theoperation of the clutches. Thus, the manufacturing process is alsosimplified and made more efficient.

The invention has been described in an illustrative manner. It is to beunderstood that the terminology, which has been used is intended to bein the nature of words of description rather than of limitation. Manymodifications and variations of the invention are possible in light ofthe above teachings. Therefore, within the scope of the claims, theinvention may be practiced other than as specifically described.

1. A dual clutch transmission having radially nested clutchescomprising: an outer clutch having a plurality of first outer clutchdisks, a plurality of first inner clutch disks, and a first outersupport carrier, said first inner clutch disks and said first outerclutch disks operatively interleaved between each other, said firstouter clutch disks operatively mounted to said first outer supportcarrier; an inner clutch having a plurality of second outer clutchdisks, a plurality of second inner clutch disks, and a second innersupport carrier, said second inner clutch disks and said second outerclutch disks operatively interleaved between each other, said secondinner clutch disks operatively mounted to said second inner supportcarrier; and a common disk carrier having a common clutch disk carrierthat operatively supports said first inner clutch disks of said outerclutch and said second outer clutch disks of said inner clutch.
 2. Adual clutch transmission as set forth in claim 1 that further includes afirst actuating piston adapted to cause said first inner and said firstouter disks of said outer clutch to operatively engage each other, and asecond actuating piston adapted to cause said second inner and saidsecond outer disks of said inner clutch to operatively engage eachother.
 3. A dual clutch transmission as set forth in claim 2 thatfurther includes a guide cylinder wherein said first actuating piston isdisposed between said guide cylinder and said common disk carrier suchthat said guide cylinder and said first actuation piston form a pressurechamber that is adapted to be pressurized to cause said first actuatingpiston to actuate said outer clutch, and said first actuation piston andsaid common disk carrier form a compensation chamber that is adapted tobe pressurized to compensate for excess outer clutch actuation pressure.4. A dual clutch transmission as set forth in claim 2 that furtherincludes a compensating piston wherein said second actuating piston isdisposed between said compensating piston and said common disk carriersuch that said common disk carrier and said second actuation piston forma pressure chamber that is adapted to be pressurized to cause saidsecond actuating piston to actuate said inner clutch, and said secondactuation piston and said compensating piston form a compensationchamber that is adapted to be pressurized to compensate for excess innerclutch actuation pressure.
 5. A dual clutch transmission as set forth inclaim 1 wherein said first actuating piston includes a plurality ofcircumferentially extending tabs and said common disk carrier includes alike plurality of corresponding openings such that said extending tabsextend though said openings to operatively engage said outer clutchassembly.